1. Field of the Invention:
This application relates to electromagnetic pumps for molten metals, and more particularly, to a pump that includes a rotational flow guide or inducer at the inlet and a rotational to axial flow converting inductor located in the region of the pump outlet.
2. Description of the Prior Art:
Electromagnetic pumps are known in the prior art. One class of device is described by Fenemore in U.S. Pat. No. 2,786,416. Operation of the described device relies on the use of a rotating magnetic field which generates currents in fluids within a cylindrical duct. Such currents interact with the magnetic field to produce a forward propelling force in the fluid. Fluid enters the duct by means of inlet ports aligned with the duct axis. A thin-walled cylindrical inner tube, filled with iron powder to concentrate the magnetic lines of flux in the region of the fluid flow, is located within the duct. Pumps of this design have inherent problems in that the pumping efficiency from inlet to output suffers from cavitation losses due to the simultaneous presence of gas and liquid within the duct. Also, since a fluid is introduced axially, an amount of additional energy is required in order to initiate rotational flow in the fluid.
Additionally, the interior shape of the duct and the enclosed cylinder does not efficiently provide for increase in velocity head as the fluid travels through the pump. It is thought that the Fenemore construction results in cavitation losses.
Another problem of the device described is the lack of an efficient means of conversion from velocity head to pressure head at the output of the pump.
Another such pump is described by Ingels in U.S. Pat. No. 2,929,326. Operation of the described pump here again relies upon the use of a rotating magnetic field to generate a forward propelling force on a molten metal that is introduced into the duct of the pump. The described device does not provide for initiating rotational flow in the fluid that enters the pump, nor is there provision for efficient conversion of the velocity head in the molten metal to the pressure head at the exit port of the pump. Thus, significant energy loss is experienced in using pumps of such design.